Safety contact plug



June 27. 1933.

C. A. GOOD SAFETY CONTACT PLUG Origihal Filed Feb; 7, 1930 R0 m my mad/am N v T H8 C Y B a Patented June 27, 1933 EJ'NITED STATES ATENT OFFiCE SAFETY CONTACT PLUG Application filed February 7, 1930, Serial No. 426,568. Renewed November 16, 1932.

This invention relates to detachable contact devices for connecting electric irons, toasters, and other appliances, with a source of electricity, and more particularly has to do with improvements in contact plugs of the type shown in my applications for patent Serial Numbers 362,885 and 339,937 filed May 14, 1929 and October 16, 1929 respectively.

I It has been the practice to provide in contact devices of the character described a push button or similar means for the purpose of disengaging or displacing the contact memhere which are locked together or which must be displaced in order to be inserted into contacting position or to be adjusted or moved from one contacting position to another such position. Such manual displacement of contact members is often accompanied by a dangerous arcing across the separated contacts due to the absence of the quick separa tion or snap action such as required in switches. Accordingly one of the objects of my invention is to provide a contact plug in which a push button or like means may be advantageously used to facilitate a quick and proper insertion and adjustment of the plug into an operative position without causing arcing of the current between the contact members as heretofore took place upon the push button manipulation as aforementioned.

- A further object of my invention is to provide a contact plug of the character described in which engagement and disengagement of the contact members without the snap action necessary to prevent arcing can only take place when the electrical current supply to said members is shut off.

Another object is to provide a contact plug of the character described in which a switch is arranged to lock the push button against operation when the switch is closed and to release the push button when the switch is open, the said switch being operable at all times, however, regardless of the position and relative arrangement of the contact or push button, whereby a convenient control of the circuit is provided at a point close to the electric device or appliance being used.

"Further it is an object of my invention to 0 provide a plug of the character described in which the contact members releasably lock against accidental displacement from contacting position when the push button displacing means is released following an insertion of the plug into operative relation to its companion contact device, but readily release and permit of withdrawal of the plug whena force is intentionally applied to with draw the plug.

The invention possesses other objeotsand features of advantage, some of which, with tl e foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of the speciiication. It is to be understood, however, that variations in the showing made by the said drawing and description may be adopted within the scope of the invention as set forth in the claims. 0

Referring to said drawing:

Figure 1 represents a top plan of the plug with the upper half of the body removed and showing the parts in position as when the switch is on and the push button is locked, 75 and also showing the plug operatively associated with a companion contact device.

Figure 2 is a view similar to Figure 1 showing the parts as when the switch is off and the push button is free to be operated. 7 80 Figure 3 is a side elevation of the complete plug and associated contact device.

The embodiment of my invention as shown in detail in the accompanying drawing comprises a sectional plug body member 3 formed. of insulation material and provided with compartments 4, 5 and 6 in which are housed preferably resilient contact members 7 and 8 and the switch means 9. At the end the body has an opening 10 for conductors 11 and at the other end thereof the compartments 4: and 5 are open to permit the insertion therein of contact members 12 and 13 of a contact device it such as provided on an electric iron or other electric appliance. On one side the body has an opening 15 in which a push button 16 is slidably mounted in such manner that when depressed will displace the contact member 8 laterally inward. Operated by the 0 switch 9 is a means for releasably looking the push button, and comprises as here shown a detent plunger 17 arranged to be moved into locking position to prevent operation of the push button when the switch is on and to be withdrawn and permit operation of the push button when the switch is off.

The contact members 7 and 8 are flexibly or yieldably secured at their inner ends to contact elements 18 and 19 secured in the body 3. One conductor 11 is connected with the contact element 18. The other is connected with a stationary switch contact element 20 which is arranged to extend close to but to remain spaced from the contact element 19, electrical connection between these con t-acts being made through the switch 9. The switch includes a pivoted lever or handle 21 extending through a slot 22 on one side of the body. Pivoted on the lever is a switch blade 23 arranged with a spring in such manner that it will move quickly or snap into and out of operative position when the lever is moved. In its operative position the switch engages the contact elements 19 and 20 and thereby electrically connects the plug contact member 8. In its other position as shown in Figure 2 the switch blade is moved clear of the contact elem nt 19 for the contact member 8.

Both the contacts 7 and 8 are arranged to move laterally. Particularly is the contact 8 displaced inwardly whereby the lower out- Wardly bent or hooked end 28 thereof may be moved inwardly. In order to provide for a locking action of the contact 8 with the contact 13, the latter is formed with shoulders 30 under and with which the terminal 28 cooperates in such manner that the contacts are held against accidental separation but when intentionally pulled will separate. To insure this releasable locking action springs 31 are arranged-to urge the contacts 7 and 8 outwardly for close frictional and locking engagement with the contacts 12 and 13.

In order to bring the contacts 7 and 8 into operative contact with the contacts 12 and 13, it is necessary to displace one of the contacts inwardly and as here shown the push button 16 provides for so displacing the contact8. In this connection it will be noted that the contact12 may be inclined or otherwise disposed whereby the outer end thereof is spaced outward from the plane of the end 27 of the contact 7 to insure an unobstructed movement of these two contacts into operative relation. On the other hand the contact 13 is so constructed and arranged that unless the end 28 of the contact 8 is displaced the two contacts could not be engaged in proper contactual relation. In some instances the contact 13 may be of sectional construction, that is, composed of a series of individual spaced contacts 34: each connected with a separate electrical element not here shown but after the manner shown in my application Serial No. 399,937 aforementioned. l/Vith this type of sectional contact, adjustment of the plug contact 8 into different contact sections 34 is desirable. Such adjustment in an outward direction is readily permitted and is free from arcing owing to the snap action of the contact 8 in moving out of contact with the shoulders 30 which it will be noted are provided in each contact section 34. However, lateral displacement of the contact 8 while the switch is on would cause dangerous arcing at the spaced contacts and to avoid this the detent 17 is arranged to be extended into and remain in a slot 35 in the push button when the switch is closed. This will cause the lower edge 37 of the opening 15 to fit snugly in the notch 38 in the push button and lock the button against movement while the switch is maintained in circuit position as shown in Figure 1. WVith this arrangement no movement of the contacts 7 and 8 not accompanied by the non-arcing snap motion as when the end 28 moves clear of the shoulder 30, will be permitted when the switch is on. However, when the switch is turned off the detent 17 is withdrawn from the slot 35 in such manner as to lift the button and move the notch 38 clear of the edge 37, the friction of engagement of the parts holding the button in raised position is such that it may be readily operated to depress the contact 8for purposes of adjusting or first engaging the contacts 7 and 8 with the contacts 12 and'13. In this connection it will be noted that the slot 35 is slightly inclined so as to be angularly disposed relative to the detent 17 whereby the frictional engagement of the detent and buttonis increased and the lifting of the button as aforesaid will be insured. The coasting portions of the edge 37 and notch 38 are such that when the button is pushed inward it will tend to move upward and free the notch 38 from the edge 37. Thus it will be seen that when the detent 37 is in place in the slot 35 no such upward movement of the button is permitted and the button cannot be pushed inward. Owing to this arrangement even if the button does not remain lifted as aforementioned, when the switch is thrown ofi, it may be operated to depress. the contact 8.

I dispose the plugin operative position relative to an associated contact device, such for example, as the one 14 here shown, the switch must be in circuit opening position shown in Figure 2. 'With the plug thusan ranged the operator holds the plug with the push button depressed. and thereby displaces the contact 8 into a position such that the lower end 28 thereof may be moved down past and clear of contact with the outer end of the contact member 13. The contact 7 clears the outer end of the contact 12 and thus the plugmay be inserted or moved to cause the contacts 12 and 13 to extend into the compartments 4 and 5 into position to cause the shoulder 30 thereof to be engaged by the hook end 28 of the contact 8. On releasing the push button the contacts 7 and 8, due to their inherent resiliency and the springs 31, will move into proper cont-actual relation with the contacts 12 and 13 and will be locked against accidental disengagement therewith by the ends 27 and 28 and the contacts 12 and 13. As the switch isoff when the contacts are allowed to engage no arcing will take place. After such engagement the switch is thrown on and the electrical connection is made and employed in the usual manner. Should it be desired toadjust contact 8 to engage a particular one of the separate contacts 34 an outward adjustment of the plug for such purpose may be readily efiected, the end 28 of contact 8 readily moving with a snap action clear of the shoulders 30 and moving with a similar snap action into engagement with the next contact 34:. Thus no arcing will take place. However should an inward adjustment of the plug be required,

say to move the plug from the position shown in Figure 1 to its inner position, it is necessary to displace the contact 8 before such adjustment may be effected. In order to depress the push button 16 to thereby displace the contact, it is necessary to open the switch and thus unlock the button. With the button unlocked it will be clear that the contact may be safely displaced and safely adjusted as desired without danger of arcing. After adjustment the switch is thrown on and the connection used in the usual manner.

It will now be apparent that I have combined a switch in a contact plug in a novel manner, whereby not only is a convenient control of the circuit. afforded at the plug, but other advantages are made possible. Among these advantages are the automatic locking of the plug against accidental disengagement with its associated contact, and the provision for engaging and disengaging and adjusting the contacts without danger of arcing.

I claim:

1. In a contact device, a body member, a contact member carried by said body, means for displacing said contact member, a switch carried by the body and operable to electrically connect and disconnect said contact with an electric circuit, and means operating to prevent operation of said displacing means when the switch is in circuit closing position and releasing said displacing means when said switch is moved to open the circuit.

2. In a contact device, a body member, a yieldable contact member carried by said body, means for forcing said contact into operative position, means for displacing said contact member out of operative position, a switch carried by the body and operable to electrically connect and disconnect said contact with an electric circuit, and means operating to prevent operation of said displacing means when the switch is in circuit closing position and releasing said displacing means when said switch is moved to open the circuit.

3. In a contact device separable body members, contacts on said members arranged to separably engage one another, a circuit closer carried by one of said members and arranged to connect and disconnect one ofthe contacts with an electrical circuit, means for displacing one of said contacts from a contacting position thereof, and means operating to prevent operation of said displacing means when the circuit closer is in circuit closing position, and permitting operating of said displacing means when. the circuit closer is in position to open the circuit.

4. In a contact device a body member, a contact member normally disposed in position to be engaged with another contact, means on said body manually operable to displace said contact member from its normal position and from a contacting position thereof, and means preventing operation of said displacing means while said contact'is electrically connected with a source of electricity.

5. In a contact device separable body members, contacts on said members arranged to be yieldingly engaged with one another, means providing for a snap movement of certain of said contacts out of contacting position incident to an intentional application of a separating force thereto, means on one of sai members manually operable to displace one of said contacts from a contacting position, and means preventing operation of said manually operable displacing means while said displaceable contact is in electrical connection with a source of electricity.

6. In a contact device a body, contact members carried by said body, a switch arranged on said body to connect and disconnect one of said contact members with an electrical circuit, a push button on said body arranged to be depressed to displace one of said contact members from a contacting position, and a member carried by said switch and movable thereby to engage and prevent actuation of the push button when the switch is disposed in circuit closing position.

7 In a contact device a body, contact members carried by said body, a switch arranged on said body to connect and disconnect one of said contact members with an electrical circuit, a push button on said body arranged to be depressed to displace one of said contact members from a contacting position, a member carried by said switch and movable thereby to engage and prevent actuation of the push button when the switch is disposed in circuit closing position, and coacting portions on the body and push button operating to prevent actuation of the push button position, coacting portions on the button and body acting to prevent operation of the button when the button is disposed in a predetermined position, and a member operated by the switch to move said button intoand out of said predetermined position. a

Intestimony whereof I have hereunto'set my hand at Oakland, California, this 15th day of January 1930. v v

CHARLES A. GOOD. 

